Oil refinery minimizes manual tank measurements

A major European oil company upgraded its refinery as part of a strategy to enhance plant profitability, increase throughput capacity, upgrade product yields and improve on-stream reliability.

A major European oil company upgraded its refinery as part of a strategy to enhance plant profitability, increase throughput capacity, upgrade product yields and improve on-stream reliability.

One of the upgrades performed at the refinery was the integration of an automated tank gauging system (ATG).

Traditionally, the operation collected data manually from their farm of tanks.

Twice a day a group of people were deployed to visit every tank, climb to the top, measure tank levels using a stick, record the information and then enter it into the refinery's tank information system (TIS).

The logistics of climbing on the tanks and exposure to potentially inclement weather posed considerable safety concerns.

As well, the data collected was not accurate as temperature can significantly impact the volume of a tank.

Consider, for example, that a change in temperature requires corrected level values which account for the thermal expansion of the tank walls.

A manual reading out by 1mm and multiplied by 74 tanks can cause a significant discrepancy between actual and recorded inventory levels.

Also consider the impact of a tank that leaks.

This causes serious repercussions not just for the industry, but for the environment as well.

In addition, the time consuming manual gauging process meant data was not available in real-time to plant operators and key decision makers.

Last, manual data entry errors would sometimes mean that inventory was incorrectly calculated.

The automated tank gauging system enabled terminal operators to have easy real-time access to all measured and calculated parameters, such as level, temperature, flow, density, gross and net standard volumes.

The continuous accurate monitoring of tanks makes it possible for the company to deal with tank level uncertainties representing significant potential losses and maintain good overall inventory management.

How did they do it? Part of the company's strategy involved upgrading their plant's control system with a Yokogawa Centum Control System (CS).

The old Bailey control system was retained because it had proprietary software tools still used by operators.

The company's Control Engineer explained: "The automated tank gauging project installed field instrumentation on the tanks spread across the Refinery".

"Field IO (input/output) consisted of Foundation Fieldbus fed into a Yokogawa Centum CS".

However, in order for operators to access the data through the Bailey dependent order management system (OMS) and TIS, they needed to take the accurate real-time field data captured in the new Yokogawa Centum CS and transfer it to the Bailey DCS".

The oil company needed to interface between two disparate control systems.

One option was to write proprietary interfaces, however this would require weeks of custom coding, delay implementation and drive up costs.

Another would be to use OPC standards based connectivity technology.

OPC is a technology used to transfer data among devices and applications which, compared with the proprietary method, is an inexpensive, easy to use, and commercially off-the-shelf solution.

Based on industrial connectivity standards, it is quick to integrate and provides a stable, secure and reliable environment.

For these reasons, the oil company opted to integrate the OPC standards based connectivity solution.

The refinery faced three main integration issues: the Bailey control system was old and not equipped with an OPC interface; it needed a way to facilitate the transfer of tag data from the Yokogawa Centum CS to the Bailey system; and the Yokogawa Centum CS and the Bailey system were on different Window domains which complicates Windows DCOM configuration.

To enable the Bailey system with OPC, the control engineer opted to integrate the MatrikonOPC Server for Bailey.

"OPC gives us the flexibility to expand; it enables us to add data from any other OPC-compliant system", commented the integrator.

"In this case it was the Yokogawa Centum CS, but it can be from other control systems as well".

"So we can extend the life of our legacy applications without sacrificing the new features of the latest control systems".

Next, since the tank gauging hardware was interfaced with the Yokogawa but the visualisation tools were connected to the Bailey system, the company needed a way to transfer data from one control system to the other.

MatrikonOPC's Data Manager is an off-the-shelf solution that transfers data between control systems.

But because the control systems were on different Window domains, there were DCOM issues.

To overcome the final issue, the refinery opted to use OPC Tunnelling technology to handle the DCOM problems.

OPC Tunnelling is a secure and reliable way to transfer data between different domains.

Once MatrikonOPC's Tunneller was installed on the network of each domain, MatrikonOPC Data Manager could seamlessly transfer data between the two systems.

When the project was complete, the refinery had a robust solution providing true interoperability that was easy to integrate all with commercial off-the-shelf software.

The MatrikonOPC solution enabled the refinery to transfer 573 points in real-time.

The result was better analysis, precise inventory control and better management of working capital, while reducing man power costs, incorrect data entry, and safety concerns.

Both short and long-term facility performance has improved to help the company achieve operational excellence.

Tank inventory data can now be easily exchanged and in addition, the refinery has realised a fully scalable solution for future changes and expansion making it possible to continue as a pacesetter in the industry.

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